With the recent popularization of portable electronics such as cellular phones, notebook-sized personal computers and video camcorders as well as vehicles such as hybrid electric cars, a demand for batteries for use in the driving power sources of those devices and vehicles is growing.
As the batteries used in such applications, lithium ion secondary batteries (hereinafter referred to as “batteries”) are widely known which use a positive electrode plate for a lithium ion secondary battery (hereinafter referred to as “positive electrode plate”), the positive electrode plate having positive active material layers laid over the main surfaces, respectively, of a positive current collecting foil made of aluminum.
For example, Patent Literature 1 discloses a battery using a positive electrode (a positive electrode plate) in which active material layers (positive active material layers) containing active material are formed on a current collector (a positive current collecting foil). This current collector is made of aluminum and has surfaces (main surfaces) which have been made porous by AC etching. This battery is able to exhibit good charge/discharge properties because it can retain electrolyte in the holes of the current collector (the positive current collecting foil).